Protein folding stress in the endoplasmic reticulum of a cell initiates a signal transduction cascade termed the unfolded protein response or UPR. A key enzyme, inositol requiring enzyme 1 (IRE-1α), relieves protein folding stress by enhancing molecular chaperone activity and therefore protects cells from stress induced apoptosis. Inhibitors of IRE-1α are useful for treating at least B cell autoimmune diseases, certain cancers, and some viral infections.